Verry big bootcamp - boot up problem.

Hello There,

Yesterday i was making some preparations for installing Windows7, but i wasn't going to install it yet.

So i made a partation for Windows with Bootcamp, after that i quitted Bootcamp and turned the Mac off.

But now when i boot up my Mac, i keeps starting from the Windows7 partition in MS-DOS mode.

Which (because i don't have a installion disc yet) is only a black screen saying: 'No disc detected, please insert a installation cd and press continue.' or something like that.

I already tried to turn it off and on, but it didn't help.

Anyone can help me?

Thank you for your time and help!

Finn